CBSE Class 11 Chemistry Hydrocarbons Worksheet

Question- 2-Methylbutane on reacting with bromine in the presence of sunlight gives mainly

(a) 1-bromo-3-methylbutane

(b) 2-bromo-3-methylbutane

(c) 2-bromo-2-methylbutane

(d) 1-bromo-2-methylbutane'

Answer-(c)

Question- Which of the following gas is find in coal mines and marshy places?

(a) Methane

(b) Ethane

(c) Benzene

(d) Propane

Answer-(a)

Question- How many isomers are possible for the C₅H₁₂ ?

(a) 2

(b) 3

(c) 4

(d) 5

Answer-(b)

Question- Which of the following does not belong to the same homologous series?

(a) CH₄

(b) C₂H₆

(c) C₃H₈

(d) C₄H₈

Answer-(d)

Question- The number of chain isomers possible for the hydrocarbon C₅H₁₂ is

(a) 1

(b) 2

(c) 3

(d) 4

Answer-(c)

Question- The number of primary, secondary and tertiary carbons in 3, 4-dimethylheptane are respectively

(a) 4, 3 and 2

(b) 2, 3 and 4

(c) 4, 2 and 3

(d) 3, 4 and 2

Answer-(a)

Question- Which of the following statements is false for isopentane–

(a) It has three CH₃ groups

(b) It has one CH₂ group

(c) It has one CH group

(d) It has a carbon which is not bonded to hydrogen

Answer-(d)

Question- Molecular formula of which of the following alkane can exist in more than one structure ?

(a) CH₄

(b) C₂H₆

(c) C₃H₈

(d) C₄H₁₀

Answer-(d)

Question- Methane, ethane and propane are said to form a homologous series because all are

(a) hydrocarbons

(b) saturated compounds

(c) aliphatic compounds

(d) differ from each other by a CH₂ group

Answer-(d)

Question- The number of 4° carbon atoms in 2,2,4,4-tetramethyl pentane is –

(a) 1

(b) 2

(c) 3

(d) 4

Answer-(b)

Question- Which of the following fuel cause the least pollution ?

(a) Petrol

(b) CNG

(c) Kerosene

(d) LPG

Answer-(d)

Question- The reaction, CH3-Br + 2Na + Br – CH3 → the product, is called

(a) Wurtz reaction

(b) Perkin’s reaction

(c) Aldol condensation

(d) Levit reaction

Answer-(a)

Question- Which one of the following gives only one monochloro derivative?

(a) n-hexane

(b) 2-methylpentane

(c) 2, 3-dimethylpentane

(d) neo-pentane

Answer-(d)

Question- Pure methane can be produced by

(a) Wurtz reaction

(b) Kolbe’s electrolytic method

(c) Soda-lime decarboxylation

(d) Reduction with H₂

Answer-(c)

Question- Which one of the following has the least boiling point?

(a) 2, 2– dimethylpropane

(b) n-butane

(c) 2-methylpropane

(d) n-pentane

Answer-(a)

Hydrocarbons MCQ Questions with Answers Class 11 Chemistry

Question- Which one of the following cannot be prepared by Wurtz reaction ?

(a) CH₄

(b) C₂H₆

(c) C₃H₈

(d) C₄H₁₀

Answer-(a)

Question-How many conformations are possible for ethane ?

(a) 2

(b) 3

(c) infinite

(d) one

Answer-(c)

Question- Sodium salts of carboxylic acids on heating with soda lime give alkanes containing _______ than the carboxylic acid.

(a) one carbon more

(b) one carbon less

(c) two carbon less

(d) Either (a) or (b)

Answer-(b)

Question-The restricted rotation about carbon-carbon double bond in 2- butene is due to

(a) overlap of one s- and one sp²-hybridized orbitals

(b) overlap of two sp²-hybridized orbitals

(c) overlap of one p-and one sp²-hybridized orbitals

(d) sideways overlap of two p-orbitals

Answer-(d)

Question- In the free radical chlorination of methane, the chain initiating step involves the formation of

(a) chlorine free radical

(b) hydrogen chloride

(c) methyl radical

(d) chloromethyl radical.

Answer-(a)

Question-LPG mainly contains :

(a) ethyne

(b) butane

(c) methane

(d) ethane

Answer-(d)

Question-Photochemical halogenation of alkane is an example of

(a) electrophilic substitution

(b) electrophilic addition

(c) nucleophilic substitution

(d) free radical substitution

Answer-(d)

Question-Aromatisation of n-hexane gives :

(a) cyclohexane

(b) benzene

(c) cycloheptane

(d) toluene

Answer-(b)

Question-The molecular formula of a compound in which double bond is present between C & C :

(a) C_nH_{2n + 2}

(b) C_nH_n

(c) C_nH_2n

(d) C_nH_2n–2

Answer-(c)

Question- n-Hexane isomerises in presence of anhydrous aluminium chloride and hydrogen chloride gas to give

(a) 2-Methyl pentane

(b) 3-Methyl pentane

(c) Both (a) and (b)

(d) Neither (a) nor (b)

Answer-(c)

Question-Which one of the following has highest boiling point?

(a) n-Octane

(b) 2,2 dimethyl pentane

(c) Iso-octan

(d) All have equal values

Answer-(a)

Question-Spatial arrangements of atoms which can be converted into one another by rotation around a C–C single bond are called

(a) Stereoisomers

(b) Tautomers

(c) Optical isomers

(d) Conformers

Answer-(d)

Question-Bond angle in alkenes is equal to

(a) 120°

(b) 109°28'

(c) 180°

(d) 60°

Answer-(a)

Question-Liquid hydrocarbons can be converted to a mixture of gaseous hydrocarbons by :

(a) oxidation

(b) cracking

(c) distillation under reduced pressure

(d) hydrolysis

Answer-(b)

Hydrocarbons MCQ Questions with Answers Class 11 Chemistry

Question- The alkene that exhibits geometrical isomerism is

(a) 2- methyl propene

(b) 2-butene

(c) 2- methyl -2- butene

(d) propene

Answer-(b)

Question- Reaction of HBr with propene in the presence of peroxide gives

(a) isopropyl bromide

(b) 3-bromo propane

(c) allyl bromide

(d) n-propyl bromide

Answer-(d)

Question-Alcoholic solution of KOH is used for

(a) Dehydrogenation

(b) Dehalogenation

(c) Dehydration

(d) Dehydrohalogenation

Answer-(d)

Question- Consider the following statements : A hydrocarbon of molecular formula C5H10 is a
I. monosubstituted alkene
II. disubstituted alkene
III. trisubstituted alkene
Which of the following statement(s) is(are) correct?

(a) I, II and III

(b) I and II

(c) II and III

(d) I and III

Answer-(a)

Question- Butene-1 may be converted to butane by reaction with

(a) Sn – HCl

(b) Zn – Hg

(c) Pd/H₂

(d) Zn – HCl

Answer-(c)

Question-Hex-2-ene and 2-methylpent-2-ene exhibit

(a) chain isomerism

(b) position isomerism

(c) geometrical isomerism

(d) optical isomerism

Answer-(a)

Question-By which reaction ethene is obtained from ethyne -

(a) oxidation

(b) polymerisation

(c) hydrogenation

(d) dehydrogenation

Answer-(c)

Question-The major product formed when 2-bromobutane is treated with alcoholic KOH is

(a) 2-Butanol

(b) 1-Butene

(c) 1-Butanol

(d) Trans-2-butene

Answer-(d)

Question-Which one of the following exhibits geometrical isomerism?

(a) 1, 2-dibromopropene

(b) 2, 3-dimethylbut-2-ene

(c) 2, 3-dibromobut-2-ene

(d) Both (a) and (c)

Answer-(d)

Question-When one mole of an alkene on ozonolysis produces 2 moles of propanone, the alkene is

(a) 3-methyl-1-butene

(b) 2, 3-dimethyl-1-butene

(c) 2, 3-dimethyl-2-pentene

(d) 2, 3-dimethyl-2-butene

Answer-(d)

Question-When hydrochloric acid gas is treated with propene in presence of benzoyl peroxide, it gives

(a) 2-Chloropropane

(b) Allyl chloride

(c) No reaction

(d) n-Propyl chloride.

Answer-(a)

Question-A reagent used to test unsaturation in alkene is -

(a) ammonical Cu₂Cl₂

(b) ammonical AgNO₃

(c) solution of Br₂ in CCl₄

(d) conc. H₂SO

Answer-(c)

Question-"The addition of unsymmetrical reagents to unsymmetrical alkenes occurs in such a way that the negative part of the addendum goes to that carbon atom of the double bond which carries lesser number of hydrogen atoms" is called by :

(a) Saytzeff rule

(b) Markownikoff's rule

(c) Kharasch effect

(d) Anti-Saytzeff rule

Answer-(b)

Question-Ethyl bromide gives ethylene when reacted with –

(a) ethyl alcohol

(b) dilute H₂SO₄

(c) aqueous KOH

(d) alcoholic KOH

Answer-(d)

Question-Alkenes usually show which type of reaction –

(a) addition

(b) substitution

(c) elimination

(d) superposition

Answer-(a)

Question-The total number of isomers for C₄H₈ is

(a) 5

(b) 6

(c) 7

(d) 8

Answer-(b)

Question-Polythene is a resin obtained by polymerisation of

(a) Butadiene

(b) Ethylene

(c) Methane

(d) Ethyne

Answer-(b)

Question-Paraffins are soluble in

(a) Distilled water

(b) Benzene

(c) Methanol

(d) Sea water

Answer-(b)

Question- Ethyl hydrogen sulphate is obtained by reaction of H₂SO₄ on

(a) Ethylene

(b) Ethane

(c) Ethyl chloride

(d) Ethanol

Answer-(a)

Question-  Number of alkynes for formula C₅H₈ is –

(a) 2

(b) 3

(c) 4

(d) 5

Answer-(b)

Question- The acetylene molecule contains :

(a) 5 sigma bonds

(b) 4 sigma and 1 pi bonds

(c) 3 sigma and 2 pi bonds

(d) 2 sigma and 3 pi bonds

Answer-(c)

Question-  An alkyne has general formula :

(a) C_nH₂n

(b) C_nH_2n+1

(c) C_nH_2n+2

(d) C_nH_2n-2

Answer-(b)

Question- Which of the following compounds does not follow Markownikoff’s law ?

(a) CH₃CH = CH₂

(b) CH₂CHCl

(c) CH₃CH = CHCH₃

(d) None of these

Answer-(c)

Question-  The C - H bond length is minimum in the bond formed by

(a) sp - s overlapping (as in alkynes)

(b) sp² – s overlapping (as in alkenes)

(c) sp³ – s overlapping (as in alkanes)

(d) None of these

Answer-(a)

Question- The alkene that will give the same product with HBr in the absence as well as in the presence of peroxide is

(a) 2-butene

(b) 1-butene

(c) propene

(d) 1-hexene

Answer-(a)

Question- The test for unsaturation is confirmed by the decolourisation of which of the following

(a) Iodine water

(b) CuSO₄ solution

(c) Bromine water

(d) All of these

Answer-(c)

Question- Isopropyl alcohol is obtained by reacting which of the following alkenes with conc. H2SO4 and H2O

(a) Ethylene

(b) Propylene

(c) 2-methyl propene

(d) Isoprene

Answer-(b)

Question- The negative part of an addendum adds on to the carbon atom joined to the least number of hydrogen atoms. This statement is called

(a) Thiele’s theory

(b) Peroxide effect

(c) Markownikoff’s rule

(d) Baeyer’s strain theory

Answer-(c)

Question- One mole of a symmetrical alkene on ozonolysis gives two moles of an aldehyde having a molecular mass of 44 u. The alkene is

(a) propene

(b) 1-butene

(c) 2-butene

(d) ethene

Answer-(c)

Question- The homologue of ethyne is

(a) C₂H₄

(b) C₂H₆

(c) C₃H₈

(d) C₃H₆

Answer-(d)

Question- Ethylene reacts with alkaline KMnO4 to form

(a) Oxalic acid

(b) HCHO

(c) Ethyl alcohol

(d) Glycol

Answer-(d)

Question- Maximum carbon-carbon bond distance is found in –

(a) ethyne

(b) ethene

(c) ethane

(d) benzene

Answer-(c)

Question- Ethene when treated with Br2 in the presence of CCl4 which compound is formed

(a) 1, 2-dibromoethane

(b) 1-bromo-2-chloroethane

(c) Both (a) and (b)

(d) 1, 1, 1-tribromoethane

Answer-(a)

Question- Butyne-2 contains :

(a) sp hybridised carbon atoms only

(b) sp³ hybridised carbon atoms only

(c) both sp and sp² hybridised carbon atoms

(d) both sp and sp³ hybridised carbon atoms

Answer-(d)